free software

Installing Scipy and PyNIO on a Bare Cluster with the Intel Compiler

2 years ago I had the task of running a python-program using scipy on our university cluster, using the Intel Compiler. I needed all those (as well as PyNIO and some other stuff) for running TM5 with the python shell on the HC3 of KIT.

This proved to be quite a bit more challenging than I had expected - but it was very interesting, too (and there I learned the basics of GNU autotools which still help me a lot).

But no one should have to go to the same effort with as little guidance as I had, so I decided to publish the script and the patches I created for installing everything we needed.1

The script worked 2 years ago, so you might have to fix some bits. I won’t promise that this contains everything you need to run the script - or that it won’t be broken when you install it. Actually I won’t promise anything at all, except that if the stuff here had been available 2 years ago, that could have saved me about 2 months of time (each of the patches here required quite some tracking of problems, experimenting and fixing, until it provided basic functionality - but actually I enjoyed doing that - I learned a lot - I just don’t want to be forced to do it again). Still, this stuff contains quite some hacks - even a few ugly ones. But it worked.

Installing GNU Guix 0.6, easily

Org-Source (for editing)

PDF (for printing)

“Got a power-outage while updating?
No problem: Everything still works”

GNU Guix is the new functional package manager from the GNU Project which complements the Nix-Store with a nice Guile Scheme based package definition format.

What sold it to me was “Got a power-outage while updating? No problem: Everything still works” from the Guix talk of Ludovico at the GNU Hacker Meeting 2013. My son once found the on-off-button of our power-connector while I was updating my Gentoo box. It took me 3 evenings to get it completely functional again. This would not have happened with Guix.

Update (2014-05-17): Thanks to zerwas from IRC @ freenode for the patch to guix 0.6 and nice cleanup!

Intro

Installation of GNU Guix is straightforward, except if you follow the docs, but it’s not as if we’re not used to that from other GNU utilities, which often terribly short-sell their quality with overly general documentation ☺

So I want to provide a short guide how to setup and run GNU Guix with ease. My system natively runs Gentoo, My system natively runs Gentoo, so some details might vary for you. If you use Gentoo, you can simply copy the commands here into the shell, but better copy them to a text-file first to ensure that I do not try to trick you into doing evil things with the root access you need.

In short: This guide provides the First Contact and Black Triangle for GNU Guix.

Communicating your project: honest marketing for free software projects

Communicating your project is an essential step for getting the users you want. Here I summarize my experience from working on several different projects including KDE (where I learned the basics of PR - yay, sebas!), the Hurd (where I could really make a difference by improving the frontpage and writing the Month of the Hurd), Mercurial (where I practiced the minimally invasive PR) and 1d6 (my own free RPG where I see how much harder it is to do PR, if the project to communicate is your own).

Since voicing the claim that marketing is important often leads to discussions with people who hate marketing of any kind, I added an appendix with an example which illustrates nicely what happens when you don’t do any PR - and what happens if you do PR of the wrong kind.

If you’re pressed for time and want the really short form, just jump to the questionnaire.

Use the source, Luke! — Emacs org-mode beamer export with images in figure

I just needed to tweak my Emacs org-mode to beamer-latex export to embed images into a figure environment (not wrapfigure!). After lots of googling and documentation reading I decided to bite the bullet and just read the source. Which proved to be much easier than I had expected.

This tutorial requires at least org-mode 8.0 (before that you had to use hacks to get figure without a caption). It is only tested for org-mode 8.0.2: The code you see when you read the source might look different in other versions.

default answer to “I want to connect with you on [hip unfree service]”

I just decided to give a default answer when I get some email from people asking me to connect to them on some new unfree service:

Hello [Person],

You asked me to connect with you on some unfree service. If you still want that, just use a status.net-server. Those are federated, so you can use a number of different providers and still be connected to everyone on any other server.

Surprising behaviour of Fortran (90/95)

1 Introduction

I recently started really learning Fortran (as opposed to just dabbling with existing code until it did what I wanted it to).

Here I document the surprises I found along the way.

If you want a quick start into Fortran, I’d suggest to begin with the tutorial Writing a commandline tool in Fortran and then to come back here to get the corner cases right.

As reference: I come from Python, C++ and Lisp, and I actually started to like Fortran while learning it. So the horror-stories I heard while studying were mostly proven wrong. I uploaded the complete code as base60.f90.

Equal-Area Map Projections with Basemap and matplotlib/pylab

PDF (read as slides)

Org (reproduce)

Plotting global equal area maps with python, matplotlib/pylab and Basemap.

Table of Contents

Basic usecases for DVCS: Workflow Failures

If you came here searching for a way to set the username in Mercurial: just run hg config --edit and add
    [ui]
    username = YOURNAME <EMAIL>
to the file which gets opened. If you have a very old version of Mercurial (<3.0), open $HOME/.hgrc manually.

Update (2015-02-05): For the Git breakage there is now a partial solution in Git v2.3.0: You can push into a checked out branch when you prepare the target repo via git config receive.denyCurrentBranch updateInstead, but only if nothing was changed there. This does not fully address the workflow breakage (the success of the operation is still state-dependent), but at least it makes it work. With Git providing a partial solution for the breakage I reported and Mercurial providing a full solution since 2014-05-01, I call this blog post a success. Thank you Git and Mercurial devs!

Update (2014-05-01): The Mercurial breakage is fixed in Mercurial 3.0: When you commit without username it now says “Abort: no username supplied (use "hg config --edit" to set your username)”. The editor shows a template with a commented-out field for the username. Just put your name and email after the pre-filled username = and save the file. The Git breakage still exists.

Update (2013-04-18): In #mercurial @ irc.freenode.net there were discussions yesterday for improving the help output if you do not have your username setup, yet.

1 Intro

I recently tried contributing to a new project again, and I was quite surprised which hurdles can be in your way, when you did not setup your environment, yet.

So I decided to put together a small test for the basic workflow: Cloning a project, doing and testing a change and pushing it back.

I did that for Git and Mercurial, because both break at different points.

I’ll express the basic usecase in Subversion:

  • svn checkout [project]
  • (hack, test, repeat)
  • (request commit rights)
  • svn commit -m "added X"

You can also replace the request for commit rights with creating a patch and sending it to a mailing list. But let’s take the easiest case of a new contributor who is directly welcomed into the project as trusted committer.

dvcs-basic-svn.png

A slightly more advanced workflow adds testing in a clean tree. In Subversion it looks almost like the simple commit:

dvcs-basic-svn-testing.png

Babcore: Emacs Customizations everyone should have

Update (2017-05): babcore is at 0.2, but I cannot currently update the marmalade package. See lisplets/babcore.el

1 Intro

PDF-version (for printing)

Package (to install)

orgmode-version (for editing)

repository (for forking)

project page (for fun ☺)

Emacs Lisp (to use)

I have been tweaking my emacs configuration for years, now, and I added quite some cruft. But while searching for the right way to work, I also found some gems which I direly miss in pristine emacs.

This file is about those gems.

Babcore is strongly related to Prelude. Actually it is just like prelude, but with the stuff I consider essential. And staying close to pristine Emacs, so you can still work at a coworkers desk.

But before we start, there is one crucial piece of advice which everyone who uses Emacs should know:

C-g: abort

Hold control and hit g.

That gets you out of almost any situation. If anything goes wrong, just hit C-g repeatedly till the problem is gone - or you cooled off far enough to realize that a no-op is the best way to react.

To repeat: If anything goes wrong, just hit C-g.

wisp: Whitespace to Lisp

» I love the syntax of Python, but crave the simplicity and power of Lisp.«

display "Hello World!" ↦ (display "Hello World!")
define : factorial n     (define (factorial n)            
    if : zero? n       ↦     (if (zero? n)                
       . 1                      1                      
       * n : factorial {n - 1}  (* n (factorial {n - 1}))))

Wisp basics

»ArneBab's alternate sexp syntax is best I've seen; pythonesque, hides parens but keeps power« — Christopher Webber in twitter, in identi.ca and in his blog: Wisp: Lisp, minus the parentheses
☺ Yay! ☺
with (open-file "with.w" "r") as port
     format #t "~a\n" : read port
Familiar with-statement in 25 lines.

 ↓ skip updates ↓

Update (2018-06-26): There is now a wisp tutorial for beginning programmers: “In this tutorial you will learn to write programs with wisp. It requires no prior knowledge of programming.”Learn to program with Wisp, published in With Guise and Guile
Update (2017-11-10): wisp v0.9.8 released with installation fixes (thanks to benq!). To start your own wisp-project, see the tutorial Starting a wisp project. For more info, see the NEWS file. To test wisp v0.9.8, install Guile 2.0.11 or later and bootstrap wisp:
wget https://bitbucket.org/ArneBab/wisp/downloads/wisp-0.9.8.tar.gz;
tar xf wisp-0.9.8.tar.gz ; cd wisp-0.9.8/;
./configure; make check;
examples/newbase60.w 123
If it prints 23 (123 in NewBase60), your wisp is fully operational.
That’s it - have fun with wisp syntax!
Update (2017-10-17): wisp v0.9.7 released with bugfixes. To start your own wisp-project, see the tutorial Starting a wisp project. For more info, see the NEWS file. To test wisp v0.9.7, install Guile 2.0.11 or later and bootstrap wisp:
wget https://bitbucket.org/ArneBab/wisp/downloads/wisp-0.9.7.tar.gz;
tar xf wisp-0.9.7.tar.gz ; cd wisp-0.9.7/;
./configure; make check;
examples/newbase60.w 123
If it prints 23 (123 in NewBase60), your wisp is fully operational.
That’s it - have fun with wisp syntax!
Update (2017-10-08): wisp v0.9.6 released with compatibility for tests on OSX and old autotools, installation to guile/site/(guile version)/language/wisp for cleaner installation, debugging and warning when using not yet defined lower indentation levels, and with wisp-scheme.scm moved to language/wisp.scm. This allows creating a wisp project by simply copying language/. A short tutorial for creating a wisp project is available at Starting a wisp project as part of With Guise and Guile. For more info, see the NEWS file. To test wisp v0.9.6, install Guile 2.0.11 or later and bootstrap wisp:
wget https://bitbucket.org/ArneBab/wisp/downloads/wisp-0.9.6.tar.gz;
tar xf wisp-0.9.6.tar.gz ; cd wisp-0.9.6/;
./configure; make check;
examples/newbase60.w 123
If it prints 23 (123 in NewBase60), your wisp is fully operational.
That’s it - have fun with wisp syntax!
Update (2017-08-19): Thanks to tantalum, wisp is now available as package for Arch Linux: from the Arch User Repository (AUR) as guile-wisp-hg! Instructions for installing the package are provided on the AUR page in the Arch Linux wiki. Thank you, tantalum!
Update (2017-08-20): wisp v0.9.2 released with many additional examples including the proof-of-concept for a minimum ceremony dialog-based game duel.w and the datatype benchmarks in benchmark.w. For more info, see the NEWS file. To test it, install Guile 2.0.11 or later and bootstrap wisp:
wget https://bitbucket.org/ArneBab/wisp/downloads/wisp-0.9.2.tar.gz;
tar xf wisp-0.9.2.tar.gz ; cd wisp-0.9.2/;
./configure; make check;
examples/newbase60.w 123
If it prints 23 (123 in NewBase60), your wisp is fully operational.
That’s it - have fun with wisp syntax!
Update (2017-03-18): I removed the link to Gozala’s wisp, because it was put in maintenance mode. Quite the opposite of Guile which is taking up speed and just released Guile version 2.2.0, fully compatible with wisp (though wisp helped to find and fix one compiler bug, which is something I’m really happy about ☺).
Update (2017-02-05): Allan C. Webber presented my talk Natural script writing with Guile in the Guile devroom at FOSDEM. The talk was awesome — and recorded! Enjoy Natural script writing with Guile by "pretend Arne" ☺

presentation (pdf, 16 slides) and its source (org).
Have fun with wisp syntax!
Update (2016-07-12): wisp v0.9.1 released with a fix for multiline strings and many additional examples. For more info, see the NEWS file. To test it, install Guile 2.0.11 or later and bootstrap wisp:
wget https://bitbucket.org/ArneBab/wisp/downloads/wisp-0.9.1.tar.gz;
tar xf wisp-0.9.1.tar.gz ; cd wisp-0.9.1/;
./configure; make check;
examples/newbase60.w 123
If it prints 23 (123 in NewBase60), your wisp is fully operational.
That’s it - have fun with wisp syntax!
Update (2016-01-30): I presented Wisp in the Guile devroom at FOSDEM. The reception was unexpectedly positive — given some of the backlash the readable project got I expected an exceptionally sceptical audience, but people rather asked about ways to put Wisp to good use, for example in templates, whether it works in the REPL (yes, it does) and whether it could help people start into Scheme. The atmosphere in the Guile devroom was very constructive and friendly during all talks, and I’m happy I could meet the Hackers there in person. I’m definitely taking good memories with me. Sadly the video did not make it, but the schedule-page includes the presentation (pdf, 10 slides) and its source (org).
Have fun with wisp syntax!
Update (2016-01-04): Wisp is available in GNU Guix! Thanks to the package from Christopher Webber you can try Wisp easily on top of any distribution:
guix package -i guile guile-wisp
guile --language=wisp
This already gives you Wisp at the REPL (take care to follow all instructions for installing Guix on top of another distro, especially the locales).
Have fun with wisp syntax!
Update (2015-10-01): wisp v0.9.0 released which no longer depends on Python for bootstrapping releases (but ./configure still asks for it — a fix for another day). And thanks to Christopher Webber there is now a patch to install wisp within GNU Guix. For more info, see the NEWS file. To test it, install Guile 2.0.11 or later and bootstrap wisp:
wget https://bitbucket.org/ArneBab/wisp/downloads/wisp-0.9.0.tar.gz;
tar xf wisp-0.9.0.tar.gz ; cd wisp-0.9.0/;
./configure; make check;
examples/newbase60.w 123
If it prints 23 (123 in NewBase60), your wisp is fully operational.
That’s it - have fun with wisp syntax!
Update (2015-09-12): wisp v0.8.6 released with fixed macros in interpreted code, chunking by top-level forms, : . parsed as nothing, ending chunks with a trailing period, updated example evolve and added examples newbase60, cli, cholesky decomposition, closure and hoist in loop. For more info, see the NEWS file.To test it, install Guile 2.0.x or 2.2.x and Python 3 and bootstrap wisp:
wget https://bitbucket.org/ArneBab/wisp/downloads/wisp-0.8.6.tar.gz;
tar xf wisp-0.8.6.tar.gz ; cd wisp-0.8.6/;
./configure; make check;
examples/newbase60.w 123
If it prints 23 (123 in NewBase60), your wisp is fully operational.
That’s it - have fun with wisp syntax! And a happy time together for the ones who merge their paths today ☺
Update (2015-04-10): wisp v0.8.3 released with line information in backtraces. For more info, see the NEWS file.To test it, install Guile 2.0.x or 2.2.x and Python 3 and bootstrap wisp:
wget https://bitbucket.org/ArneBab/wisp/downloads/wisp-0.8.3.tar.gz;
tar xf wisp-0.8.3.tar.gz ; cd wisp-0.8.3/;
./configure; make check;
guile -L . --language=wisp tests/factorial.w; echo
If it prints 120120 (two times 120, the factorial of 5), your wisp is fully operational.
That’s it - have fun with wisp syntax!
Update (2015-03-18): wisp v0.8.2 released with reader bugfixes, new examples and an updated draft for SRFI 119 (wisp). For more info, see the NEWS file.To test it, install Guile 2.0.x or 2.2.x and Python 3 and bootstrap wisp:
wget https://bitbucket.org/ArneBab/wisp/downloads/wisp-0.8.2.tar.gz;
tar xf wisp-0.8.2.tar.gz ; cd wisp-0.8.2/;
./configure; make check;
guile -L . --language=wisp tests/factorial.w; echo
If it prints 120120 (two times 120, the factorial of 5), your wisp is fully operational.
That’s it - have fun with wisp syntax!
Update (2015-02-03): The wisp SRFI just got into draft state: SRFI-119 — on its way to an official Scheme Request For Implementation!
Update (2014-11-19): wisp v0.8.1 released with reader bugfixes. To test it, install Guile 2.0.x and Python 3 and bootstrap wisp:
wget https://bitbucket.org/ArneBab/wisp/downloads/wisp-0.8.1.tar.gz;
tar xf wisp-0.8.1.tar.gz ; cd wisp-0.8.1/;
./configure; make check;
guile -L . --language=wisp tests/factorial.w; echo
If it prints 120120 (two times 120, the factorial of 5), your wisp is fully operational.
That’s it - have fun with wisp syntax!
Update (2014-11-06): wisp v0.8.0 released! The new parser now passes the testsuite and wisp files can be executed directly. For more details, see the NEWS file. To test it, install Guile 2.0.x and bootstrap wisp:
wget https://bitbucket.org/ArneBab/wisp/downloads/wisp-0.8.0.tar.gz;
tar xf wisp-0.8.0.tar.gz ; cd wisp-0.8.0/;
./configure; make check;
guile -L . --language=wisp tests/factorial.w;
echo
If it prints 120120 (two times 120, the factorial of 5), your wisp is fully operational.
That’s it - have fun with wisp syntax!
On a personal note: It’s mindboggling that I could get this far! This is actually a fully bootstrapped indentation sensitive programming language with all the power of Scheme underneath, and it’s a one-person when-my-wife-and-children-sleep sideproject. The extensibility of Guile is awesome!
Update (2014-10-17): wisp v0.6.6 has a new implementation of the parser which now uses the scheme read function. `wisp-scheme.w` parses directly to a scheme syntax-tree instead of a scheme file to be more suitable to an SRFI. For more details, see the NEWS file. To test it, install Guile 2.0.x and bootstrap wisp:
wget https://bitbucket.org/ArneBab/wisp/downloads/wisp-0.6.6.tar.gz;
tar xf wisp-0.6.6.tar.gz; cd wisp-0.6.6;
./configure; make;
guile -L . --language=wisp
That’s it - have fun with wisp syntax at the REPL!
Caveat: It does not support the ' prefix yet (syntax point 4).
Update (2014-01-04): Resolved the name-clash together with Steve Purcell und Kris Jenkins: the javascript wisp-mode was renamed to wispjs-mode and wisp.el is called wisp-mode 0.1.5 again. It provides syntax highlighting for Emacs and minimal indentation support via tab. You can install it with `M-x package-install wisp-mode`
Update (2014-01-03): wisp-mode.el was renamed to wisp 0.1.4 to avoid a name clash with wisp-mode for the javascript-based wisp.
Update (2013-09-13): Wisp now has a REPL! Thanks go to GNU Guile and especially Mark Weaver, who guided me through the process (along with nalaginrut who answered my first clueless questions…).
To test the REPL, get the current code snapshot, unpack it, run ./bootstrap.sh, start guile with $ guile -L . (requires guile 2.x) and enter ,language wisp.
Example usage:
display "Hello World!\n"
then hit enter thrice.
Voilà, you have wisp at the REPL!
Caveeat: the wisp-parser is still experimental and contains known bugs. Use it for testing, but please do not rely on it for important stuff, yet.
Update (2013-09-10): wisp-guile.w can now parse itself! Bootstrapping: The magical feeling of seeing a language (dialect) grow up to live by itself: python3 wisp.py wisp-guile.w > 1 && guile 1 wisp-guile.w > 2 && guile 2 wisp-guile.w > 3 && diff 2 3. Starting today, wisp is implemented in wisp.
Update (2013-08-08): Wisp 0.3.1 released (Changelog).

Tail Call Optimization (TCO), dependency, broken debug builds in C and C++ — and gcc 4.8

TCO: Reducing the algorithmic complexity of recursion.
Debug build: Add overhead to a program to trace errors.
Debug without TCO: Obliterate any possibility of fixing recursion bugs.

“Never develop with optimizations which the debug mode of the compiler of the future maintainer of your code does not use.”°

UPDATE: GCC 4.8 gives us -Og -foptimize-sibling-calls which generates nice-backtraces, and I had a few quite embarrassing errors in my C - thanks to AKF for the catch!

1 Intro

Tail Call Optimization (TCO) makes this

def foo(n):
    print(n)
    return foo(n+1)
foo(1)

behave like this

def foo(n):
    print(n)
    return n+1
n = 1 while True: n = foo(n)

Motivation and Reward

Debunking the myth that you can increase the performance of creative workers with carrot and stick.

Update: Good fixed income and long term contracts are a tool to allow people to work full-time without reducing their motivation. They avoid the harmful effect performance-based payment can have on performance while enabling people to work full-time on a project. An empirical study found, that the source and intensity of motivation of free software developers does not differ significantly between people who work for hire and people who work without payment, so many companies employing free software developers seem to do it right (or only the companies who do it right can keep their free software programmers).1

Executive Summary

For creative tasks, the quality of performance strongly correllates with intrinsic motivation: Being interested in the task itself.

This article will only talk about that.

The main factors which are commonly associated with intrinsic motivation are:

  • Positive verbal feedback which increases intrinsic motivation.
  • Payment independent of performance which actually has no effect.
  • Payment dependent on performance which reduces the motivation on the long term.
  • Negative verbal feedback which directly reduces intrinsic motivation.
  • Threatening someone with punishment which strongly reduces intrinsic motivation.

To make it short: Anything which diverts the focus from the task at hand towards some external matter (either positive or negative) reduces the intrinsic motivation and that in turn reduces work performance.

If you want to help people perform well, make sure that they don’t have to worry about other stuff besides their work and give them positive verbal feedback about the work they do.

Note: In the paper »Why Hackers Do What They Do: Understanding Motivation and Effort in Free/Open Source Software Projects« from 2005, Karim R. Lakhani and Robert G Wolf showed empirically that the payment people get to work in free software projects has no detrimental effect on their intrinsic motivation. In their sample 40% of the developers were paid for their work on free software projects and their intrinsic motivation was as high as the motivation of unpaid developers.


  1. We find […], that enjoyment-based intrinsic motivation, namely how creative a person feels when working on the project, is the strongest and most pervasive driver. The source and intensity of motivation of free software developers does not differ significantly between people who work for hire and people who work without payment. From Why Hackers Do What They Do: Understanding Motivation and Effort in Free/Open Source Software Projects by Karim R. Lakhani* and Robert G Wolf** from the * MIT Sloan School of Management | The Boston Consulting Group and ** The Boston Consulting Group. 

Neither Humble nor Indie Bundle

Update 2016: Later Bundles seem to have gotten better again.

Comment to New Humble Bundle Is Windows Only, DRM Games.

The new Humble Indie Bundle is no longer free, indie, cross-plattform or user-respecting.

When the first bundle had a huge boost in last-minute sales after the devs offered to free the source of 4 of the 5 games, I had hoped, they would keep that.

How to make companies act ethically

→ comment on Slashdot concerning Unexpected methods to promote freedom?

Was it really Apple who ended DRM? Would they have done so without the protests and evangelizing against DRM? Without protesters in front of Apple Stores? And without the many people telling their friends to just not accept DRM?

That “preaching” created a situation where Apple could reap monetary gain from doing the right thing.

Insert a scaled screenshot in emacs org-mode

@marjoleink asked on identi.ca1, if it is possible to use emacs org-mode for showing scaled screenshots inline while writing. Since I thought I’d enjoy some hacking, I decided to take the challenge.

It does not do auto-scaling of embedded images, as far as I know, but the use case of screenshots can be done with a simple function (add this to your ~/.emacs or ~/.emacs.d/init.el):


  1. Matthew Gregg: @marjoleink "way of life" thing again, but if you can invest some time, org-mode is a really powerful note keeping environment. → Marjolein Katsma: @mcg I'm sure it is - but seriously: can you embed a diagram2 or screenshot, scale it, and link it to itself? 

  2. For diagrams, you can just insert a link to the image file without description, then org-mode can show it inline. To get an even nicer user-experience (plain text diagrams or ascii-art), you can use inline code via org-babel using graphviz (dot) or ditaa - the latter is used for the diagrams in my complete Mercurial branching strategy

Emacs

Cross platform, Free Software, almost all features you can think of, graphical and in the shell: Learn once, use for everything.

» Get Emacs «

Emacs is a self-documenting, extensible editor, a development environment and a platform for lisp-programs - for example programs to make programming easier, but also for todo-lists on steroids, reading email, posting to identi.ca, and a host of other stuff (learn lisp).

It is one of the origins of GNU and free software (Emacs History).

In Markdown-mode it looks like this:

Emacs mit Markdown mode

Creating nice logs with revsets in Mercurial

In the mercurial list Stanimir Stamenkov asked how to get rid of intermediate merges in the log to simplify reading the history (and to not care about missing some of the details).

Update: Since Mercurial 2.4 you can simply use
hg log -Gr "branchpoint()"

I did some tests for that and I think the nicest representation I found is this:

hg log -Gr "(all() - merge()) or head()"

This article shows examples for this.

Background of Freenet Routing and the probes project (GSoC 2012)

The probes project is a google summer of code project of Steve Dougherty intended to optimize the network structure of freenet. Here I will give the background of his project very briefly:

The Small World Structure

Minimal example for literate programming with noweb in emacs org-mode

If you want to use the literate programming features in emacs org-mode, you can try this minimal example to get started: Activate org-babel-tangle, then put this into the file noweb-test.org:

Minimal example for noweb in org-mode

* Assign 

First we assign abc:

#+begin_src python :noweb-ref assign_abc
abc = "abc"
#+end_src

* Use

Then we use it in a function:

#+begin_src python :noweb tangle :tangle noweb-test.py
def x():
  <<assign_abc>>
  return abc

print(x())
#+end_src

noweb-test.org

Install and setup infocalypse on GNU/Linux (script)

Update (2015-11-27): The script works again with newer Freenet versions.

Install and setup infocalypse on GNU/Linux:

setup_infocalypse_on_linux.sh

Just download and run1 it via

wget http://draketo.de/files/setup_infocalypse_on_linux.sh_.txt
bash setup_infocalypse*

This script needs a running freenet node to work! → Install Freenet

In-Freenet-link: CHK@rtJd8ThxJ~usEFOaWAvwXbHuPC6L1zOFWtKxlhUPfR8,21XedKU8YbKPGsYWu9szjY7hChX852zmFAYuvyihOd0,AAMC--8/setup_infocalypse_on_linux.sh

The script allows you to get and setup the infocalypse extension with a few keystrokes to be able to instantly use the Mercurial DVCS for decentral, anonymous code-sharing over freenet.

« Real Life Infocalypse »
DVCS in the Darknet. The decentralized p2p code repository (using Infocalypse)


  1. On systems based on Debian or Gentoo - including Ubuntu and many others - this script will install all needed software except for freenet itself. You will have to give your sudo password in the process. Since the script is just a text file with a set of commands, you can simply read it to make sure that it won’t do anything evil with those sudo rights

Custom link completion for org-mode in 25 lines (emacs)

Update (2013-01-23): The new org-mode removed (org-make-link), so I replaced it with (concat) and uploaded a new example-file: org-custom-link-completion.el.
Happy Hacking!

1 Intro

I recently set up custom completion for two of my custom link types in Emacs org-mode. When I wrote on identi.ca about that, Greg Tucker-Kellog said that he’d like to see that. So I decided, I’d publish my code.

Reducing the Python startup time

The python startup time always nagged me (17-30ms) and I just searched again for a way to reduce it, when I found this:

The Python-Launcher caches GTK imports and forks new processes to reduce the startup time of python GUI programs.

Python-launcher does not solve my problem directly, but it points into an interesting direction: If you create a small daemon which you can contact via the shell to fork a new instance, you might be able to get rid of your startup time.

To get an example of the possibilities, downl

El Kanban Org: parse org-mode todo-states to use org-tables as Kanban tables

Kanban for emacs org-mode.

Update (2013-04-13): Kanban.el now lives in its own repository: on bitbucket and on a statically served http-repo (to be independent from unfree software).

Update (2013-04-10): Thanks to Han Duply, kanban links now work for entries from other files. And I uploaded kanban.el on marmalade.

Some time ago I learned about kanban, and the obvious next step was: “I want to have a kanban board from org-mode”. I searched for it, but did not find any. Not wanting to give up on the idea, I implemented my own :)

The result are two functions: kanban-todo and kanban-zero.

“Screenshot” :)

TODODOINGDONE
Refactor in such a way that the
let Presentation manage dumb sprites
return all actions on every command:
Make the UiState adhere the list of
Turn the model into a pure state

Read your python module documentation from emacs

I just found the excellent pydoc-info mode for emacs from Jon Waltman. It allows me to hit C-h S in a python file and enter a module name to see the documentation right away. If the point is on a symbol (=module or class or function), I can just hit enter to see its docs.

pydoc in action

Exploring the probability of successfully retrieving a file in freenet, given different redundancies and chunk lifetimes

In this text I want to explore the behaviour of the degrading yet redundant anonymous file storage in Freenet. It only applies to files which were not subsequently retrieved.

Every time you retrieve a file, it gets healed which effectively resets its timer as far as these calculations here are concerned. Due to this, popular files can and do live for years in freenet.

The “Apple helps free software” myth

→ Comment to “apple supports a number of opensource projects. Webkit and CUPS come to mind”.

Apple supports a number of copyleft projects, because they have to.

Effortless password protected sharing of files via Freenet

TL;DR: Inserting a file into Freenet using the key KSK@<password> creates an invisible, password protected file which is available over Freenet.

Often you want to exchange some content only with people who know a given password and make it accessible to everyone in your little group but invisible to the outside world.

Until yesterday I thought that problem slightly complex, because everyone in your group needs a given encryption program, and you need a way to share the file without exposing the fact that you are sharing it.

Then I learned two handy facts about Freenet:

  • Content is invisible to all but those with the key
    <ArneBab> evanbd: If I insert a tiny file without telling anyone the key, can they get the content in some way?
    <evanbd> ArneBab: No.

  • You generate a key from a password by using a KSK-key
    <toad_> dogon: KSK@<any string of text> -> generate an SSK private key from the hash of the text
    <toad_> dogon: if you know the string, you can both insert and retrieve it

In other words:

Just inserting a file into Freenet using the key KSK@<password> creates an invisible, password protected file which is shared over Freenet.

Shackle-Feats: The poisoned Apple

This is a mail I sent as listener comment to Free as in Freedom.

Hi Bradley, Hi Karen,

I am currently listening to your Steve Jobs show (yes, late, but time is scarce these days).

And I side with Karen (though I use KDE): Steve Jobs managed to make a user interface which feels very natural. And that is no problem in itself. Apple solved a problem: User interfaces are hard to use for people who don’t have computer experience and who don’t have time to learn using computers right.

Richard M. Stallman stands for Free Software

→ a comment to 10 Hackers Who Made History by Gizmodo.

As DDevine says, Richard Stallman is no proponent of Open Source, but of Free Software. Open Source was forked from the Free Software movement to the great displeasure of Stallman.

He really does not like the term Open Source, because that implies that it is only about being able to read the sources.

Different from that, Free Software is about the freedom to be in control of the programs one uses, and to change them.

More exactly it defines 4 Freedoms:

50€ for the Freenet Project - and against censorship

As I pledged1, I just donated to freenet 50€ of the money I got back because I cannot go to FilkCONtinental. Thanks go to Nemesis, a proud member of the “FiB: Filkers in Black” who will take my place at the Freusburg and fill these old walls with songs of stars and dreams - and happy laughter.

It’s a hard battle against censorship, and as I now had some money at hand, I decided to do my part (freenetproject.org/donate.html).


  1. The pledge can be seen in identi.ca and in a Sone post in freenet (including a comment thread; needs a running freenet node (install freenet in a few clicks) and the Sone plugin). 

Inhalt abgleichen
Willkommen im Weltenwald!
((λ()'Dr.ArneBab))



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